David Letterman pays emotional tribute to Robin Williams

Of all the late-night hosts, David Letterman had the closest and longest personal connection to Robin Williams. Though Letterman was on vacation last week, he made sure to pay tribute to his friend on Monday's show.

Williams was found dead in his Tiburon, Calif., home last Monday after he took his own life at age 63. Williams' widow, Susan Schneider, released a statement to the media revealing that the comedian had been dealing with depression and a previously undisclosed diagnosis of Parkinson's disease.

Letterman said he and Williams were friends for 38 years. The "Late Show" host spent 10 minutes at his desk during the first half of his show recalling Williams and their early days together in the late 1970s at the Comedy Store in Los Angeles.